1. Field of the Invention
The invention is related to a carpet mat and a moldable automotive carpet.
2. Description of the Prior Art
Molded automotive carpets and mats are typically made using tufted structures where the pile yarn is tufted into a planar spunbonded sheet, the tufts secured to the sheet, and the sheet then attached to a sound deadening backing to form a planar carpet. In the tufting process a significant amount of costly pile yarn is on the side of the spunbonded sheet that attaches to the backing. With very short pile heights the pile yarn wastefully buried in the backing makes up a large percentage of the pile yarn used.
To shape the carpet it is placed between platens in a press. The platen contacting the backing is heated to permanently secure the carpet to the backing. The carpet may also be molded and formed to the desired shape in the press. If it is desired to mold and shape the carpet the backing must be deformable.
The pile yarn is typically a xe2x80x9csinglesxe2x80x9d (versus two or more yarns ply-twisted) bulked continuous filament (xe2x80x9cBCFxe2x80x9d) yarn with relatively straight filaments that is cut to give a velour appearance. Such a carpet requires a separate tufted sheet formation step and a laminating step to join it to a backing. During molding to a shape there is sometimes a problem of separation of the rows of tufts during severe deformation required in some molds. This can be compensated by adding more rows of tufts to the entire tufted sheet, but this results in a higher cost carpet.
There is a need to simplify this process to reduce pile yarn waste and reduce costs without sacrificing quality.
Tuftstrings and tuftstring carpets are disclosed in U.S. Pat. No. 5,547,732 (Edwards et al.), but the preferred embodiments there shown are intended for residential use on flat floors and are not adapted to reheating and forming. This patent does not teach use of a heavy sound deadening backing nor variation of tuft spacing that accommodates stretching during forming. It discloses an elongated pile article or xe2x80x9ctuftstringxe2x80x9d made using yarn comprising filaments attached to a support strand. In a preferred embodiment, the yarn is a ply-twisted bundle of filaments suitable for use in a cut pile residential carpet having a 38.1 mm (xc2xd inch) pile height. This preferred pile yarn does not produce the velour look preferred for automotive carpets or mats. In one described embodiment of this patent the individual yarns remain plied together when cut so the pile provides tuft definition at the top surface of the carpet after assembly of the tuftstrings into a carpet. If the pile yarn along the length of the strand is examined the individual pile yarns can be identified and there is little or no entanglement between individual pile yarns along the length of the strand. All of the filaments in the pile yarns are also biased upward since they are bonded while bent over a ridge on a mandrel and the filaments are preferably all entangled or ply twisted together into a bundle. Such a preferred configuration of pile yarn is useful when arranged in a final carpet structure, but it can be a problem when storing tuftstring in a wound package before assembly into a carpet, and when handling tuftstring at high speed during assembly into a carpet.
With the preferred tuftstring of the Edwards et al. patent, when trying to get all the filaments to lie in a ribbon-like plane for winding, it is difficult to get the individual pile yarns aligned in the same direction without some yarns crossing the strand either over the top or bottom of the strand. The individual yarns can act independently with some yarns going one way and other yarns another. This is a particular problem if the chosen strand does not have any significant torsional stability. The upward configuration of all the filaments in the pile yarns also contributes to difficulties getting all the individual pile yarns bent into a flat ribbon for efficient winding. When guiding the preferred tuftstrings for assembly into a carpet the above problems associated with individual pile yarns acting independently makes guiding difficult, especially with a strand that has low torsional stability. Special guides are disclosed for handling tuftstrings described in Edwards et al. in the carpet-making process disclosed in related publications WO96/06685 (Popper et al.) and WO97/06003 (Agreen et al.) (now U.S. Pat. No. 5,804,008. U.S. Pat. No. 5,804,008 is hereby incorporated herein by reference.
It is important that all pile yarn be oriented upright in the carpet assembly. If the tuftstring flips over due to torsional instability, and it is bonded to a backing in that orientation, the carpet assembly will be rejected.
The Popper et al. publication also teaches a process for making moisture stable tuftstring carpets using ultrasonic energy for bonding the tuftstrings to a backing substrate. A preferred nylon carpet construction uses a nylon tuftstring having the nylon ply-twisted tufts of the Edwards et al. patent attached to a nylon covered strand which has a fiberglass core. This tuftstring is bonded to a backing substrate comprising a fiberglass scrim placed between two layers of non-bonded, nonwoven nylon sheet to make a moisture stable carpet. Such a backing is lightweight and flexible and is designed to be the final backing for a residential carpet. The pile yarn lacks the desired look for an automotive carpet and the backing is costly to use as an intermediate backing for an automotive carpet construction that requires a layer of heavy sound absorbing material for the backing. The glass scrim in the backing and the glass in the strand would make the carpet inelastic so stretching and drawing would not be possible.
The present invention is directed toward a pile article (tuftstring) structure suitable for automotive pile surface structures (carpet, mat or door panel) that is easy to guide for carpet forming and it is easy to form into a flat ribbon-like configuration suitable for winding into a package. The tuftstring has a pile yarn comprising BCF singles yarn, that is not twisted, ply-twisted, or otherwise entangled to form individual tufts, and that is cut to a pile height of less than 12.7 mm (xc2xd inch) and preferably less than 6.4 mm (xc2xc inch). The strand can be a torsionally stable one with an uninterrupted outer surface, or one with a glass core with a wrapped staple yarn sheath that has little torsional stability. The tuftstring so made surprisingly has a beneficial geometry for high speed handling and flat winding. The filaments in the yarn are distributed along the length of the strand in a monolithic loosely entangled array of filaments extending outward from the strand in two spaced apart pile rows which provide some torsional stability to the tuftstring structure. By torsional stability is meant that a 38.1 mm (1xc2xd inch) length can be twisted one hundred eighty (180) degrees about the axis of the strand and the pile yarn will still retain a monolithic structure without the filaments separating, and the tuftstring will return to near the original configuration unaided and without evidence that it has been twisted.
The distribution of the filaments about the strand has a surprising configuration. Looking at the cross-section of the tuftstring there are filaments along a lower side of each row that lie within ten (10) degrees to a plane defined at the base of the tuftstring. The remaining filaments for each row are continuously distributed through an angular sector, having an origin in the base plane aligned with the width of the strand, that extends from the lower side of the row to an upper side that falls between forth five (45) and ninety (90) degrees from the base and leaves a space between the two rows that is at least equal to the width of the strand. This space between the rows is important for inserting a guide member that contacts the strand without trapping filaments between the guide member and the strand. The filaments at the lower side of the rows are in a position suitable for flat winding and they are entangled with the remaining filaments which is believed to facilitate flattening of the pile rows for flat winding. The entanglement of the upper side filaments with the lower side filaments also is believed to restrain the filaments at the upper side of the rows from coming together and closing the space over the strand that must be kept open for high speed guiding of the tuftstring. The filaments at the upper side of the rows are in a position suitable for forming a carpet pile surface when assembled with a backing substrate. The entanglement of the lower side filaments with the upper side filaments is believed to facilitate reorienting the lower side filaments upward during carpet formation.
The arrangement of filaments is especially useful in an automotive carpet mat when the strand used is comprised of a core of continuous glass filaments and at least one multifilament yarn wrapped at least partially around said core, although such a strand has low resistance to torsional twisting. The resulting tuftstring made with this strand is torsionally stable due to the arrangement of filaments in the pile structure. The glass in the tuftstring provides a level of moisture and thermal stability for a mat that must lay flat under gravity and is not draw molded.
The arrangement of filaments is especially useful in an automotive molded carpet when the strand comprises a support strand having an uninterrupted outer surface (which may include a monofilament or extruded sheath/core). Such a strand should also be permanently drawable free of fracture up to fifteen percent (15%) at a draw temperature of one hundred fifty (150) degrees C. and a draw force of 8.9 N (2 pounds) or less at said draw temperature, to thereby limit the draw force required for the tuftstring. With such a strand, the force required to draw the tuftstring is kept at a low level at a desired draw temperature of one hundred thirty to one hundred eighty (130-180) degrees C. This limits distortion of the overall carpet structure during molding so lateral separation or bunching of adjacent tuftstrings can be uniformly constrained by the backing substrate and the backing substrate is not damaged.
The arrangement of filaments in the tuftstring is particularly useful when making a pile surface structure preform, such as a preform for an automotive mat or carpet, by guiding the tuftstring at high speed onto a rotating drum covered with a backing substrate and embedding the tuftstring into the surface of the backing substrate. During such operation, the filaments forming the spaced monolithic pile rows provide resistance to torsional twisting of the tuftstring to aid handling and guiding, and maintain an open space between rows for a pressing tool to engage the strand without trapping pile row filaments between the strand and the tool or between the base of the tuftstring and the backing substrate. The surface of the backing substrate where the tuftstring is embedded may be tacky or may be caused to be tacky by the application of heat, for instance.
A variety of backing substrates are useful with the tuftstrings for making the automotive mat or moldable carpet preforms. The preforms typically are subsequently processed under heat and pressure between press platens to form the finished mat or molded carpet. In one embodiment a fabric layer is added to the backing before molding to stabilize the structure during and after molding. Any time after the tuftstrings are attached to the backing substrate, the bulkable pile yarn is treated with heat, or heat and moisture, to bulk the pile yarn and eliminate the spacing between pile rows so a uniform pile surface is formed in the finished product.